WOOD'S 



OUTLINE ASTRONOMY 



FOR 



Children 14 years of age, 




SOLD BY 

J. L. HAMMETT, 

37 and 39 Brattle Street, 
BOSTON. 



# LIBRARY OF CONGRESS,! 

t 

J I'XITED STATES OF AMERICA. J 



WOOD'S 

OUTLINE ASTRONOMY: 

THE LAST OF A GRADED SERIES OF OUTLINES, 

INCLUDING 

BOTANY, PHYSIOLOGY, PHYSICS, METEOROLOGY, 
AND ASTRONOMY. 

PREPARED EXPRESSLY EOR USE IX HIS OWN SCHOOL, 

Br. 



^( 



ALLEN F. WOOD, A. M., 

MASTER OF FIFTH STREET GRAMMAR SCHOOL, 

NEW BEDFORD, MASS. 



SUITED TO USE IX AVERAGE GRAMMAR SCHOOLS, AXD 
IN HIGH SCHOOLS WITH CLASSICAL SCHOLARS 
WHOSE TIME EOR THE SCIEXCES 
IS LIMITED. 



&< 



NEW BEDFORD: 
E. Axthoxt & Sons, Printers. 

1S77. 




nr 






Entered accord ■-, In the year 1876, by 

ALLEN l WOOD, 
in the office of the Librarian i f Congress, >i Washington, 



PREFACE. 

In the progress of education, the outlines of some of the sciences 
seem to demand a place in our Grammar schools. The elements of 
Botany, Physiology, Physics, Meteorology, and Astronomy, may 
be made as useful as Geography and History, and unless they are 
taught in our Grammar schools, more than eighty per cent, of our 
children have no oppoitunity of gaining any accurate knowledge 
of them. 

The objections which are commonly urged against these elements, 
or outlines, are mainly two : first, that there is no time in the Gram- 
mar schools to give to them, and second, that the scholars are not 
able to comprehend them. 

In regard to the first of these objections, I remark that only two 
hours a week for the major portion of a year, is all that is necessary 
to complete the outlines of any one of the sciences named, and a 
four years experience shows that this amount of time can be 
devoted to these subjects, without seriously affecting the ordinary 
studies. 

In regard to the second objection, that the scholars are not capa- 
ble of comprehending these sciences, I reply that when the facts 
are properly presented, as large a proportion of the scholars com- 
prehend them, as comprehend Arithmetic, Geography, or any other 
study. 

There is another point which is sometimes urged as an objection 
to these sciences in the Grammar schools, viz., that the High school 
is a more fitting place for them; but when we consider that only 
fifteen per cent, of the scholars that enter the Grammar schools 
ever enter the High school, the argument is largely in favor of 
giving some attention to these sciences in the Grammar schools. 

The order in which these sciences should be arranged for our 
schools is that in which they were enumerated, viz., Botany, Phys- 
iology, Physics, Meteorology, and Astronomy. The principal points 
of Botany can be so stated that average children ten years old can 
understand them ; and the outlines of the other sciences can be 
introduced, one each year, as the children advance in their course 
of study. 



4 PREFACE. 

In order to make the stud}- of these sciences a success En the 
Grammar schools, two facts must be kept constantly in mind : first, 
the most important topics in each science must be chosen, and sec- 
ond, these topics must be presented in the clearest possible manner. 

To meet both of these demands without a suitable manual, is no 
easy ta>k, and, in addition to the work ordinarily required, imposes 
a heavy burden upon the teacher; for she is obliged, as she ad- 
vances with her class, not only to prepare a new outline each year, 
but to see that it is accurately copied by all her schola 

With the hope of relieving the teachers immediately associated 
with himself, and also of securing more uniform methods of teach- 
ing the - - in question, the writer has undertaken to prepare 
a brief outline of each. 1 be adapted to the 
different grades Of his BChool, and it is expected that they will all 
be ready for use before the close of the present school year. 

If these outlines should seem to meet the wants of other teach- 
ers, and should be Introduced into other schools than that for which 
they were prepai effort to lift the burden of teachers, and 

at the same time to diffuse a ki. . QQes among the 

children, will be doubly repaid. 

The Outline Astronomy Is now ready for use. It is designed for 

scholars only fourteen yei aid therefore is not a complete 

36. If any of the topics need further development, additions 
may be made upon the blank pages which have been inserted for 
the convenience of the teacher. 

The authorities which have been consulted in the preparation of 
this outline are Lockyer's >nomy, Quackenbos's 

Natural Philosophy, and Appleton*s New Cyclopedia. 

In using the book, every teacher must exercise his own judgment 
as to the best methods of teaching the subject. In his own prac- 
tice, the author I ry topic orally, when it is brought before 
the class for the first time. In doing so, he carefully explains all 
the terms and principles, and illustrates them by all the appliances 
at his command. Then, when all the terms and principles are well 
understood, he requires his scholar- to fix the outlines firmly in 
mind, and reviews them often. 

A. F. W. 

New Bedford, Dec. 19. 1876. 






ASTRONOMY. 



INTRODUCTION. 

1 . Definition.— Astronomy is the science that treats 
of the heavenly bodies, viz., the sun, moon, stars, 
planets, and comets. 

2. Number of Heavenly Bodies— The number 
of the heavenly bodies is not known, and never can be. 

3. Shape. — The shape of these bodies, or worlds as 
they are often called, is generally round. 

4. Visibility.— Very many of these bodies shed a 
light of their own, or a borrowed light, and are there- 
fore visible to the human eye. Others are non-lumin- 
ous, and consequently invisible. 

5. Groups or Systems.— All the bodies that occu- 
py space are arranged in groups or systems, and the 
members of each system take different names according 
to their peculiarities. 

6. The Sun of each System.— The most import- 
ant member of each system is its sun. It occupies a 
central position in the system, and is the source of light 
and heat to the other members. It contains more mat- 
ter than all the other members of the system, and by 
its attractive force holds them in their places; 

1 



6 ASTRONOMY. 

7. Planets Defined.— The planets in each system 
are those bodies that revolve about the sun of the 
tern, and shine by its reflected light. 

8. Moons. — Moons arc large round bodies that move 
round the planets in elliptical orbits, and shine by the 
reflected light of the sun. 

9. Stars.— Stars are bright luminous bodies seen in 
every part of the heavens at night. 

10. Comets.— ( k>mets are Luminous heavenly bodies 
which usually present long tails of light. 

SOLAR SYSTEM. 

11. The Earth a Member.— The Earth which we 
inhabit is a planet belonging to the Solar System, of 
which the Sun is the a ntre. 

12. Its Members.— Tin 1 Solar System, as known 
at present, consists of the Sun. 138 planets. 18 moons, 
and thousands of comets. 

THE SUN. 

13. Size. — The Sun is a round body, N.')3,000 miles 
in diameter. It contains many times as much matter 
as all the other members of the solar system taken to- 
gether, and by its attractive force holds them in their 
places. 

14. Constitution. — Nothing is known about the 
nature of tin 1 matter that makes np the great interior 
bulk of the Sun. In its atmosphere, the following sub- 
stances have been found to exist in the ft rm of vapor: 



ASTRONOMY. 7 

sodium, calcium, magnesium, iron, zinc, copper, and 
nickel. 

15. Motions. — The Sun has two motions, one on 
its axis in 25 days, and the other in an elliptical orbit 
in 18,000,000 years. In this latter movement the Sun, 
with all the other members of the solar system, moves 
through space at the rate of 300 miles a minute. 

16. Light. — The surface of the Sun is almost wholly 
luminous, and diffuses a bright light to all the planets. 
The intensity of the light at the different planets varies 
according to their distances from the Sun. 

17. Spots. — Dark s23ots are at times seen upon the 
surface of the Sun. They sometimes continue for 
months, sometimes only for a day or two, and they 
have been known to appear and then to disappear al- 
most instantly. 

18. Heat.— The Sun is the great source of heat to 
all the planets. The intensity of the heat at the differ- 
ent planets varies according to their distances from the 
Sun. 

PLANETS. 

19. Definition. — The planets of the solar system 
are those bodies that move around our Sun in elliptical 
orbits, ami shine by its reflected light. 

20. Number. — In the solar system there are known 
to be 138 planets. Of these, 130 are so small that 
they are called asteroids, or star-like bodies. 

21. Size. — The asteroids vary in their diameters 



8 ASTRONOMY. 

from 17 to 228 miles ; the other planets, from 3,000 to 
37,000 miles. 

22. A Planet's Distance from the Sun Vari- 
able. — The orbit being elliptical, a planet's distance 
from the Sun is constantly varying. When a planet's 
distance,' from the Sun is spoken of, its mean or average 
distance is meant. This is obtained by adding its great- 
est distance from the Sun to it< least distance, and di- 
viding by 2. 

• 

23. Perihelion and Aphelion.— That point of a 
planet's orbit which lies nearest to the Sun is called its 
perihelion ; and the point farthest distant is called its 
aphelion. 

24. Distances from the Sun.— The planets are 

not all equally distant from the Sun. but vary from 35 
millions to 27oi> millions of miles. 

25. Motions. — Every planet has two motions, one 
on its axis, and the other round the Sun. 

26. Day and Year. — The time it takes a planet to 
turn once on its axis ; - called its day, and the time it 
takes for it to go once round the Sim is called its year. 

27. Light. — The planets shine by a steady reflected 
light of the Sun. 

28. Transit. — The passage of a smaller body across 
the disk of a larger is called its transit. Thus the pas- 
sages of Mercury and Venus across the Sun's disk, are 
called, respectively, the Transit of Mercury and the 
Transit of Venus. 

20. Inferior and Superior. — Mercury and Venus 
are nearer the Sim than the Earth is, and are called 



ASTRONOMY. V 

Inferior Planets. The others are farther from the Sun 
than the Earth is, and are called Superior Planets. 

30. Names.— The following are the names of the 
planets in the order of their distances from the Sun : 
Mercury, Venus, Earth, Mars, Asteroids, Jupiter, Sat- 
urn, Uranus, and Neptune. 

The planets will now be considered in the above order. 

MEKCUKY. 

31. Position.— Mercury is the nearest planet to 
the Sun. 

32. Visibility.— It can be seen only a few times 
each year. When visible, it is just after sunset, or 
just before sunrise. At other times it is lost below the 
horizon, or in the brightness of the Sun. 

33. Light. — Unlike the other planets, it has a slight 
twinkle to its light. 

34. Solar Light and Heat— The Sun's light and 
heat at Mercury are seven times as intense as they are 
at the Earth. This fact alone makes it impossible for 
Mercury to be inhabited by creatures like ourselves. 

35. Day and Year.— -Mercury's day varies but a 
few minutes from our own, while its year is equal to 
less than three of our months. 

VENUS. 

36. Position. — Venus is the second planet from the 
Sun, and in its course comes nearer the Earth than any 
other of the planets. 



10 ASTRONOMY. 

37. Visibility. — Venus is so bright that it is some- 
times seen with the naked eye at midday. During 
parts of the year it rises before the Sun, and then is 
called the Morning Star ; at other times it rises after 
the Sun, and then i- called the Evening Star. 

38. Solar Light and Heat.— The Sun's light and 
heat at Venus are twice aa great as they are at the 
Earth, and they vary much more between the equator 
and the poles. 

39. Day and Year. — Venus's day is about half an 
hour less than our own. and its year is a little less than 
eight of our months. 

THE EARTH. 

10. Position. — The Earth on which we live is the 
third planet from the Sun. 

41. Form. — The Earth is nearly a perfect sphere, 
being flattened a little on opposite sides. The highest 
mountains are so slight when compared with the _ 
mass of the Earth, that they do not materially affect 
its shape. 

42. Diameter. — The mean diameter of the Earth 
Is 7912 miles. 

43. Surface. — The surface of the Earth is composed 
of land and water, one fourth of it being land and 
three fourths being water. 

44. Constitution. — According to present discover- 
ies, the Earth is made up of 64 substances or elements. 
The most common of these are the metals, — gold, sil- 
ver, iron, copper, mercury, lead, tin, antimony, zinc, 



ASTRONOMY. 11 

bismuth, arsenic, and nickel; and the gases, — oxygen, 
hydrogen, and nitrogen. 

45. Two Motions. — The Earth has two motions, 
one on its axis in 24 hours, and the other round the Sun 
in 3651 days. The former is called its daily motion, 
and the latter its yearly. 

4(3. Day and Night. — From the Earth's daily mo- 
tion, we have the succession of day and night. It oc- 
curs in this way. During the 24 hours, every part of 
the Earth, except small portions at the poles, conies 
into the Sun's light, and then recedes from it. While 
the Sun shines upon any place, it is day there ; during 
the rest of the 24 hours, the place is withdrawn from 
the Sun's rays, darkness reigns, and it is night there. 

47. Orbit. — The orbit of the Earth is really an 
ellipse, like that of the other planets, but it deviates 
only a little from a circle. 

48. Distance from the Sun.— The Earth's peri- 
helion is 90,000,000 miles from the Sun, and its aphe- 
lion 93,000,000 miles. During the year, the Earth's 
distance from the Sun varies between these two dis- 
tances. The mean distance may be stated at about 
92,000,000 miles. 

49. Change of Seasons. — The position of the Earth 
is such while moving round in its orbit, that the Sun's 
vertical rays strike the Earth north of the equator dur- 
ing half the year, and south of the equator during the 
rest of the year. When the Sun reaches its most 
northern point in the heavens, June 21, it gives the 
most heat to the northern hemisphere, and we have 



12 ASTRONOMY. 

summer ; at the .same time it gives the least heat to the 
southern hemisphere, and it is winter there. Six 
months later, December 21, the Sun is at its most 
Boathern point, and gives the most heat \>) the southern 
hemisphere. It i- then summer south of the equator, 
while it is winter here. In either hemisphere spring 
follows winter, and autumn, or fall, follows summer. 

Position Designated.— The position of a place 
on the Earth is designated by it- latitude and longitude. 
Thus New I is in latitude 41 

North, and longitud 

51. Significance of the Tropics.— These two 
cir« a j. north and south from the equal 
mark the .-pace beyond vrhich the Sun's rays are never 
vertical. Tiny are called tropi s, se when .the 
Sun rei m, in its apparant movement about the 
Earth, it turn- back towards r. The north- 
ern tropic is called the Tropic of Cancer, because, at 
the point of turning, the Sun is seen in that portion of 
the heaven- which - ipied by a cluster of Btars 
called Cancer. For a like reason, (he southern tropic 
is called the Troj pricorn. 

52. Polar Circles.— Tin- Arctic circle marks the 
leal portion of the northern hemisphere. It sur- 
rounds the north pole at a distant _ leg., and 
takes its name from the fact that it lies under the con- 
stellation formerly called Arcticus, but now called by 
us the Bear. The Antarctic circle surrounds the south 
pole, as the Arctic does the north, at a distance of 2?>± 
desr. It marks the coldest portion of the southern 



ASTRONOMY. 13 

hemisphere, and takes its name from the fact that it 
lies opposite to the Arctic circle. 

53. Climate, etc. — Climate and vegetation vary 
great]y between the equator and the poles, owing 
largely to the difference in direction of the Sun's rays. 

54. Direction of the Earth's Axis. -- The 
Earth's axis alwa} T s points to a place in the heavens 
near the North Star. 

55. Horizons. — The Sensible Horizon is the circle 
on the Earth's surface which bounds our view. The 
Rational Horizon is a plane passing through the centre 
of the Earth parallel to the sensible horizon, and ex- 
tending out into the heavens. 

56. Zenith— Nadir.— The Zenith is the point in 
the heavens directly over our heads. The Nadir is the 
point in the heavens directly under our feet, or in other 
words, it is the point in the heavens directly over the 
heads of our antipodes. 

57. Equinoctial.— The Equinoctial, or Celestial 
Equator, is the plane of the Earth's equator, extending 
to the heavens and dividing them as it docs the Earth. 

58. Ecliptic— The Ecliptic is the apparent path 
of the Sun. It is a great circle of the heavens, and 
cuts the equinoctial, or celestial equator, at an angle of 
231- degrees. 

59. Equinoxes.— The two points at which the 
ecliptic cuts the equinoctial are called Equinoxes, be- 
cause when the Sun reaches these points in March and 
September, the days and nights are equal all over the 
world. 



14 ASTRONOMY. 

GO. Solstices.— The Solstices are the standing-points 

of the Sun. When the Sun reaches its most northern 
limit, June 21st, it appears for several days to stand 
still, that is to move neither north nor south, and is 
then said to be at its Summer Solstice. On December 
21st, the Sun reaches its other standing-point, and is 
then said to be at its Winter Solstice. 

61. Zodiac. — The Zodiac is an imaginary belt in 
the heavens I s deg. wide, 9 deg. of which lie on each 
side of the ecliptic. It i- in the Zodiac thai wo sec the 
Sun. Moon, and all the greater planets. The entire 
belt of the Zodiac is divided into 12 signs of 30 cleg. 
each. 

62. Signs of the Zodiac— The signs of the Zo- 
diac are clusters of stars named as follows: 

Aries, the nun. Libra, the balance. 

Taurus, tin- bull. S rpio, the scorpion. 

rmini, 1 1 1 * • t\\ i ttarius, the archer. 

Caucer, t!i<' crab. Capricornus, the goat. 

Leo, the lion. Aquarius, tin- water-bearer. 

Virgo, the virgin. Pisces, the fishes. 



G3. Moon.— The Earth is attended by one moon. 

64. Size— Distance.— The Moon is 2160 miles in 
diameter, and distant from the Earth 2.°>9, 000 miles. 

65. Orbit.— The Moon's orbit is elliptical. 

66. Perigee— Apogee.— When the Moon is near- 
est to the Earth it is said to be in perigee, and when 
farthest from it, in apogee. 



ASTRONOMY. 15 

67. Motions. — The Moon turns on its axis in ex- 
actly the same time that it takes it to go once round 
the Earth. These motions are completed in about 27 
days. 

68. Light.— The Moon shines only by the reflected 
light of the Sun, and is visible at night only about half 
of each month. 

69. Phases of the Moon.— While the Moon is 
rcvolviug about the Earth, the bright surface presented 
to us is constantly changing. Hence arise the Phases 
of the Moon. 

MARS. 

70. Position. — Mars is the fourth planet in order 
of distance from the Sun, and is nearer the Earth than 
any other of the superior planets. 

71. Appearance. — Under the telescope, it sheds a 
white light from its poles, and red and green tints from 
other portions of its surface; but to the naked eye, it 
presents a reddish light. The white li^ht is supposed 
to be reflected from its snow and ice, the red light from 
its soil, and the green light from its oceans. 

72. Size. — Mars is only one sixth as large as the 
Earth. 

73. Light and Heat.— As Mars is farther from 
the Sun than the Earth is, its climate is colder than 
that of the Earth, and its light is less intense. 

74. Day and Year.— Its day is about the same as 
ours, and its year is nearly twice as long. 



1C ASTRONOMY. 

ASTEROIDS. 

75. Position. — The Asteroids are scattered in space 
between Mara and Jupiter. 

7G. Number.— It is known that there are 130 As- 
teroids, and it la believed that there are very many 
more. 

77. Visibility.— With the exception of Ceres and 
Vesta, the Asteroids arc Invisible to the naked eye. 

78. Discovery.— All the Asteroids which are now- 
known have been discovered since 1801. 

T'.'. Size. — The Asteroids are the smallest of the 
known planets, Vesta, the largest, having a diameter of 
only 228 mile-. 

80. Attraction.— The power of attraction at the 
Asteroids i- very Blight. A large man would weigh 

than one pound, and a large horse would weigh 
less than ten pounds. 

JUPITER. 

81. Position. — Jupiter lies beyond the Asteroids, 

and with the exception of these minute planets, it is 
the fifth in order of distance from the Sun. 

82. Size.— Jupiter i- tic largesl planet, and is 1200 
times as large as the Earth. 

Day and Year.— Jupiter's day is about 10 

hours long, and it- year is e<jnal to 12 of ours. 

- s 1. Moons.— Jupiter is attended by four satellites, 
or moons, three of which are larger than our own. 
Thev are invisible to the naked eve. and it is seldom 



ASTRONOMY. 17 

that their position is such that they can all be seen with 
a telescope at the same time. 

SATUKN. 

85. Position. — Saturn lies next to Jupiter, and of 
the larger planets is sixth in order of distance from the 
Sun. 

86. Size. — Saturn is next to Jupiter in size, and is 
700 times as large as the Earth. 

87. Appearance. — Saturn is not itself remarkably 
brilliant, but is surrounded by three bright rings, made 
up, it is believed, of minute satellites. 

88. Day and Year.— Saturn's day is about 10.} 
hours long, and its year is equal to 29| of ours. 

89. Moons. — Saturn is attended by eight moons, 
one of which, Titan, is the largest in the solar system. 

UK ANUS. 

90. Position.— With the exception of the Aste- 
roids, Uranus is the seventh planet in order of distance 
from the Sun, and is the outermost, but one, of all the 
known members of the planetary system. 

91. Size. — Its volume is 74 times that of the Earth. 

92. Appearance.— Owing to the great elongation 
of its orbit, its brightness varies considerably during 
its year. 

93. Day and Year. — Its day is very uncertain, but 
is thought to be about 9^ hours long. Its year is equal 
to 84 of ours. 

94. Moons. — Uranus is attended by four moons. 

b2 



18 ASTRONOMY. 

NEPTUNE. 

95. Position. — Neptune is the most distant of all 
the known planets, and, with the exception of the As- 
teroids, it is the eighth in order of distance from the 
Sun. 

96. Size. — Ita volume is l ( i"> times that of the Earth. 

97. Visibility. —Neptune is nearly three billion 
miles from the Earth, is invisible to the naked eye, and 
was not discovered by the aid of the most powerful 
telescopes till 1846. 

98. Day and Year. — The length of Neptune's day 
has not been determined, and perhaps never will be, 
inasmuch as no -put- have been discovered on it< .sur- 
face by which the period <>f it- revolution can be ascer- 
tained. In year is equal to L65 of our-. 

99. Moons. — Neptune is attended by at least one 
moon. 

ECLIPSES. 

100. Definition. — An eclipse of the Sun or Moon 
i- it- temporary obscuration by the intervention of some 
other body. When the whole disk is darkened, the 
eclipse is said to be total ; and when only a portion of 
the disk i- darkened, it i< -aid to be partial. 

101. Eclipse of the Sun.— An eclipse of the Sun 
is caused by the passage of the Moon between the Sun 
and the Earth, thus cutting oil' a part of the Sun's di- 
rect rays to the Earth. 

H>2. Eclipse of the Moon.— An celipse of the 
Moon is caused by the passage of the Earth between 



ASTRONOMY. 19 

the Sun and the Moon, thus cutting off a part of the 
Sun's direct rays to the Moon, and leaving a part of the 
Moon in darkness. 

103. Number of Eclipses.— The Sun and Moon 
may together have seven eclipses in a year, and cannot 
have less than two. They usually have four. 

COMETS. 

104. Position. — The comets are scattered at a great 
variety of distances from the Sun, some coming within 
the orbits of the planets, while others lie far beyond. 

105. Orbits. — The orbits of the comets are either 
ellipses, parabolas, or hyperbolas. If a comet has an 
elliptical orbit, it revolves around the Sun in regular 
intervals ; if it describes a parabola, or hyperbola, it 
will in time leave the solar system and seek other com- 
panions millions of miles away. 

106. Appearance.— A comet, in its most common 
form, presents three quite distinct parts. The bright- 
est of all is quite small when compared with the others, 
and is called the nucleus. Surrounding the nucleus is 
a dimmer part, called the coma, or head; and stream- 
ing from this, like hair in the wind, is a tail of light, 
which assumes a great variety of shapes. 

107. Light. — The comets shine by their own light. 
This fact is accounted for on the ground that the comets, 
unlike the planets, are all white-hot. 

108. Number.— It is thought that there are millions 
of comets belonging to the solar system, though less 
than a thousand have been actually recorded. 



20 ASTRONOMY. 

STARS. 

109. Position. — The stars arc scattered everywhere 
in space outside the solar system, and, unlike the plan- 
ets, they always seem to occupy the same positions with 
reference to each other. 

110. Magnitudes. — All the stars that are visible to 
the naked eye, arc divided, according to their bright- 
ness, into six classes, called magnitudes. The bright- 
est stars are said to be of the first magnitude, the next 
brightest of the second magnitude, and so on through 
the thirds four///. fifth, and sixth magnitude-, the last 
being so faint as scarcely to be visible. If we intro- 
duce the telescope, other stars, called Telescopic stars, 
arc brought to view. These are arranged as seventh, 
eighth, and other magnitudes, to the twentieth. 

111. Number. — The number of stars visible to the 
naked eye does not much exceed 6000, and the number 
visible at any one time does not exceed 3000. The 
number of stars that can be seen through a telescope is 
not far from 20,000,000. 

112. Distances. — The stars arc all situated at im- 
mense distance- from us. The nearest star is 20 tril- 
lions of miles away, and it took its light, travelling at 
the rate of 185,000 mile- a Becoud, three and a half 
years to reach the Earth. The light of some stars re- 
quired more than 4000 years to reach the Earth, and if 
these stars were extinguished to-day, we should enjoy 
their light for the same period of time. 

113. Light. — The stars all shine by their own light, 



ASTRONOMY. 21 

and it is probable that they are suns to systems of their 
own . 

114. Movement. — The stars, in common with our 
Sun, move around some enormous body trillions of 
miles away in space. 

115. Constellations. — The stars are divided into 
109 constellations, which take their names from animals 
and other objects to which their outline bears some 
imaginary resemblance. 

116. Galaxy —The Galaxy, or Milky Way, is an 
irregular band of light passing nearly over our heads 
in the heavens. It is composed of innumerable stars, 
which are so distant as to be distinguished only by the 
aid of the most powerful telescopes. 



TABLE OF CONTENTS. 

Pagk 

Introduction, 5 

Solar System, G 

The Sun, G 

Planets in general, 7 

Mercury, , 9 

Venus, 9 

Earth, 10 

The Mocn, 14 

Mars, . , 15 

Asteroids, 1G 

Jupiter, 16 

Saturn, 17 

Uranus, . . . 17 

Neptune, 18 

Fxlipses, 18 

Comets, 19 

Stars, 20 

Constellations, . ; 21 

Galaxy, or Milky Way, 21 



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